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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Optical Society of Korea
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Optical Society of Korea
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Volume & Issues
Volume 19, Issue 6 - Dec 2015
Volume 19, Issue 5 - Oct 2015
Volume 19, Issue 4 - Aug 2015
Volume 19, Issue 3 - Jun 2015
Volume 19, Issue 2 - Apr 2015
Volume 19, Issue 1 - Feb 2015
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Research on Subcutaneous Pulse Shape Measurement by Near-infrared Moiré Technique
Chen, Ying-Yun ; Liu, Zhizhen ; Du, Jian ; Chang, Rong-Seng ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 123~129
DOI : 10.3807/JOSK.2015.19.2.123
A pulse is generated when the heart pumps blood into the arterial system. The heart pumps blood only when it contracts, not when it relaxes; therefore, blood enters the arterial system in a cyclical form. Artery beating is visible in some parts of the body surface, such as the radial artery of the wrist. This paper mainly uses the feature in which near-infrared spectroscopy penetrates skin to construct a non-invasive measurement system that can measure small vibration in the subcutaneous tissue of the human body, and then uses it for the pulse measurement. This measurement system uses the optical moir
principle, together with the fringe displacement made by small vibration in the subcutaneous tissue, and an image analysis program to calculate the height variation from small vibrations in the subcutaneous tissue. It completes a measurement system that records height variation with time, and that together with a fast Fourier transform (FFT) program, they can convert the pulse waveform generated by vibration (time-amplitude) to heartbeat frequency (frequency-amplitude). This is a new and non-invasive medical assistance system for measuring the pulse of the human body, with the advantages of being simple, fast, safe and objective.
Influences of the Filter Effect on Pulse Splitting in Passively Mode-Locked Fiber Laser with Positive Dispersion Cavity
Chen, Xiaodong ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 130~135
DOI : 10.3807/JOSK.2015.19.2.130
Based on the extended nonlinear Schr
dinger equation, the influences of the filter effect on pulse splitting in a passively mode-locked erbium-doped fiber laser with positive dispersion cavity are investigated theoretically. Numerical results show that, as the bandwidth of the spectral filter decreases, the nonlinear chirp appended to the pulse increases under the combined action of the filter effect of the super-Gaussian spectral filter and the self-phase modulation effect. On further decreasing the bandwidth, the wave breaking of the pulse takes place. In addition, by varying the pump power of the laser or the profile of the spectral filter, the influences of the filter effect on pulse splitting also change accordingly.
Parameterized Modeling of Spatially Varying PSF for Lens Aberration and Defocus
Wang, Chao ; Chen, Juan ; Jia, Hongguang ; Shi, Baosong ; Zhu, Ruifei ; Wei, Qun ; Yu, Linyao ; Ge, Mingda ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 136~143
DOI : 10.3807/JOSK.2015.19.2.136
Image deblurring by a deconvolution method requires accurate knowledge of the blur kernel. Existing point spread function (PSF) models in the literature corresponding to lens aberrations and defocus are either parameterized and spatially invariant or spatially varying but discretely defined. In this paper, a parameterized model is developed and presented for a PSF which is spatially varying due to lens aberrations and defocus in an imaging system. The model is established from the Seidel third-order aberration coefficient and the Hu moment. A skew normal Gauss model is selected for parameterized PSF geometry structure. The accuracy of the model is demonstrated with simulations and measurements for a defocused infrared camera and a single spherical lens digital camera. Compared with optical software Code V, the visual results of two optical systems validate our analysis and proposed method in size, shape and direction. Quantitative evaluation results reveal the excellent accuracy of the blur kernel model.
Alternative Description for Gaussian Image Plane
Kim, Byongoh ; Lee, Sukmock ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 144~148
DOI : 10.3807/JOSK.2015.19.2.144
An alternative description for the Gaussian image plane (GIP) of an optical system for a given object is presented, which applies to both aberration-free and non-aberration-free systems. We extend the definition of transverse magnification (TM) to the image plane (IP) displaced from the GIP and find that the TM depends linearly on the locations of both an aperture stop placed in front of the system and the IP. Hence, we redefine the GIP as the location at which the slope of the TM variance changes sign. The definition is deterministic and self-consistent and, therefore, no other parameters or measurements are needed. The derivation of this definition using a set of paraxial ray tracings and supporting experimental data for a thick bi-convex lens system is presented.
Iterative Fourier Transform Algorithm Based on the Segmentation of Target Image for a High-Speed Binary Spatial Light Modulator
Im, Yeonsu ; Kim, Hwi ; Hahn, Joonku ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 149~153
DOI : 10.3807/JOSK.2015.19.2.149
A digital micro-mirror device (DMD) has the potential to modulate an incident wave with high speed, and the application for holographic display has been studied by many researchers. However, the quality of reconstructed image isn`t good in comparison with that from a gray-scale amplitude-only hologram since it is a binary amplitude-only spatial light modulator (SLM). In this paper, we suggest a method generating a set of binary holograms to improve the quality of the reconstructed image. Here, we are concerned with the case for which the object plane is positioned at the Fourier domain of the plane of the SLM. In this case, any point in the Fourier plane is related to all points in the hologram. So there is a chance to generate a set of binary holograms illuminated by incident wave with constant optical power. Moreover, we find an interesting fact that the quality of reconstructed image is improved when the spatial frequency bandwidth of the binary hologram is limited. Therefore, we propose an iterative segmentation algorithm generating a set of binary holograms that are designed to be illuminated by the wave with constant optical power. The feasibility of our method is experimentally confirmed with a DMD.
Wavelength-Swept Cascaded Raman Fiber Laser around 1300 nm for OCT Imaging
Lee, Hyung-Seok ; Lee, Hwi Don ; Jeong, Myung-Yung ; Kim, Chang-Seok ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 154~158
DOI : 10.3807/JOSK.2015.19.2.154
We experimentally demonstrated a novel wavelength-swept laser using a cascaded Raman gain around 1310 nm. A 1064/1310 wavelength division multiplexing (WDM) coupler and coupled fiber Bragg gratings mirrors at 1064, 1117, 1175, 1240 nm are effectively used to increase the power efficiency in a laser ring cavity with highly non-linear fiber (HNLF) of 2 km. Linear wavelength sweeping is demonstrated with the 100 Hz triangular driving signal to fiber Fabry-Perot tunable filter (FFP-TF) around the 1310 nm region. The measured sweeping range and output power were 27 nm and 2.1 mW, respectively, which are suitable for optical coherence tomography (OCT) imaging.
Simulation Study of Injection-Molded Light Guide Plates for Improving Luminance Uniformity Based on the Measured Replication Quality of Micro-Patterns for LED TV Backlight
Joo, Byung-Yun ; Ko, Jae-Hyeon ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 159~164
DOI : 10.3807/JOSK.2015.19.2.159
In the injection-molded light guide plate the replication quality, i.e. the reproduction accuracy, of micro-patterns should be high and uniform over the entire surface area. However technical difficulty in meeting the necessary replication quality arises as the plate size becomes large for TV applications. We propose a simulation technique to optimize the distribution of micro-patterns on a 55-inch injection molded light guide plate considering non-ideal replication quality of micro-patterns. The luminance uniformity could be improved by more than 16% by optimizing the pattern distribution in spite of the same replication quality.
Talbot Interferometry for Measuring the Focal Length of a Lens without Moiré Fringes
Lee, Sukmock ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 165~168
DOI : 10.3807/JOSK.2015.19.2.165
A simple method to determine the focal length of a lens using the Talbot image is presented. This method uses only one grating, requiring neither Moir
fringe analysis nor the angle between the gratings. The original Fourier transform was used to access the spectrum beyond the limitation set of the usual fast Fourier transform to determine the (de)magnification accurately enough to be used for the focal length. A set of Talbot images simulated numerically with the Fresnel diffraction integral was used to demonstrate the method. For focal lengths between 5550 mm and 5650 mm, the mean difference between the focal lengths determined from the Talbot images and the true values was 3.3 mm with the standard deviation of the difference being 3.8 mm. The true focal lengths can be recovered with an accuracy of 0.06%.
The Optical Measurement and Quantitative Analysis of Algesia in Spodoptera litura Larva
Chen, Ying-Yun ; Chang, Rong-Seng ; Tsai, Mi-Yin ; Chen, Der-Chin ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 169~174
DOI : 10.3807/JOSK.2015.19.2.169
Muscle vibration measurement has long been an unique scientific study, in general, and the direct reaction of animals to feel pain (algesia), either from vascular or muscle contraction, is a complex perceptual experience. Thus this paper proposes a way to measure animal algesia quantitatively, by measuring the changes in muscle vibration due to a pinprick on the surface of the skin of a Spodoptera litura larva. Using the laser optical triangulation measurement principle, along with a CMOS image sensor, linear laser, software analysis, and other tools, we quantify the subtle object point displacement, with a precision of up to
, for our chosen Spodoptera litura larva animal model, in which it is not easy to identify the tiny changes in muscle contraction dynamics with the naked eye. We inject different concentrations of formalin reagent (empty needle, 12% formalin, and 37% formalin) to obtain a variety of different muscle vibration frequencies as the experimental results. Because of the high concentrations of reagent applied, we see a high frequency shift of muscle vibration, which can be presented as pain indices, so that the algesia can be quantified.
Feasibility Study of Determining the Healing Phase of Achilles Tendon Rupture in Rats Using Optical Coherence Tomography
Kim, Young-Sik ; Chae, Yu-Gyeong ; Jeon, Min Yong ; Kim, Dong Kyu ; Ahn, Yeh-Chan ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 175~181
DOI : 10.3807/JOSK.2015.19.2.175
Optical coherence tomography (OCT) is a noninvasive technique for microscopic investigation of tissue. We thought that the OCT method could be a potential tool for monitoring the healing process of a tendon. In this study we used two rat models, denervated and non-denervated groups, to observe a variety of healing phases of Achilles tendon (AT) injury. We made samples of AT injury lesions, to take OCT images and to make histopathological samples of serial sectional tissue. In an OCT image the denervated rat showed no specific finding, but the non-denervated rat showed a large defect lesion that was scaffolding tissue. OCT findings combined with pathologic findings showed advantages in visualization of tendon microstructure over other imaging modalities such as MRI and US, and OCT is beneficial to making a treatment plan, especially the timing and intensity of rehabilitation. Therefore a multimodal platform using OCT for evaluation of tendon injury may be potentially useful for many applications.
Simple Graphical Selection of Optical Materials for an Athermal and Achromatic Design Using Equivalent Abbe Number and Thermal Glass Constant
Kim, Young-Ju ; Kim, Yeong-Sik ; Park, Sung-Chan ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 182~187
DOI : 10.3807/JOSK.2015.19.2.182
This paper presents a new graphical method for selecting a pair of optical glasses to simultaneously achromatize and athermalize an imaging lens made of materials in contact. An athermal glass map that plots thermal glass constant versus inverse Abbe number is derived through analysis of optical glasses and plastic materials in visible light. By introducing the equivalent Abbe number and equivalent thermal glass constant, although it is a multi-lens system, we have a simple way to visually identify possible optical materials. Applying this method to design a phone camera lens equipped with quarter inch image sensor having 8-mega pixels, the thermal defocuses over
are reduced to be much less than the depth of focus of the system.
Modified Airy Function Method Applied to Optical Waveguides and Quantum Tunneling: A Critical Analysis
Lee, Ki-Young ; Kim, Chul Han ; Park, Dongwook ; Kim, Chang-Min ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 188~198
DOI : 10.3807/JOSK.2015.19.2.188
The validity of applying the Modified Airy Function (MAF) method to the problems of graded-index optical waveguides and graded potential barrier analysis was critically examined. In the former case, the method yielded very accurate results from the derived eigenvalue equations. In the latter case, however, the same method produced results that deviated significantly from exact numerical results for barriers with a smooth peak. The causes of the discrepancies were investigated in detail.
Influence of the Thickness and Doping Concentration in p- and n-Type Poly-Si Layers on the Efficiency of a Solar Cell Based on a Carbon Fiber
Yoon, Min-Seok ; Shim, Young Bo ; Han, Young-Geun ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 199~205
DOI : 10.3807/JOSK.2015.19.2.199
We investigated the effects of the thickness and doping concentration in p- and n-type poly-Si layers on the performance of a solar cell based on a carbon fiber in order to improve the energy conversion efficiency of the cell. The short-circuit current density and open-circuit voltage of the carbon fiber-based solar cell were significantly influenced by the thickness and doping concentration in the p- and n-type poly-Si layers. The solar cell efficiency was successfully enhanced to ~10.5%.
ERRATUM : Efficient Logical Topology Design Considering Multiperiod Traffic in IP-over-WDM Networks
Li, Bingbing ; Kim, Young-Chon ;
Journal of the Optical Society of Korea, volume 19, issue 2, 2015, Pages 206~206
DOI : 10.3807/JOSK.2015.19.2.206